1. Field of the Invention
The present invention relates to an alternator pulley equipped with a one-way clutch. This alternator pulley is driven by the engine's crankshaft of an automobile, for example, via a belt and causes an alternator to generate electricity.
2. Description of the Related Art
An engine's crankshaft does not rotate at a constant speed but varies according to the operating condition of the vehicle in which the engine's is mounted. An alternator directly driven by such an engine's crankshaft generates electric power at efficiency proportional to the engine's output power.
Another alternator has been devised as disclosed in Unexamined Japanese Utility Model Publication No. 57-17256. This alternator is fitted with a one-way clutch. When the rotational speed of the crankshaft drops, the rotation of the rotor of the alternator is continued by making use of its inertial force, thereby enhancing the power generation efficiency of the alternator. This enhances the efficiency at which the alternator generates electricity. This one-way clutch uses rollers and is of normal construction. As the rotational speed of the crankshaft varies, the one-way clutch is switched between a free state and a locked state. In the free state the power is not transmitted, whereas in the locked state the power is transmitted.
In the related art technique described above, if the load applied by a spring of the one-way clutch is set high, when the rotational speed of the crankshaft decreases, the rollers of the one-way clutch become difficult to roll from their locked positions to their free positions. Therefore, a switching operation for interrupting the power transmission becomes delayed and so it becomes impossible to maintain the rotation of the alternator rotor at high speed. As a result, the power generation efficiency deteriorates.